Thread 1: EXC_BAD_INSTRUCTION (code=EXC_i386_INVOP, subcode=0x0) when timer calls a function - ios

Question

I got two problems, the first one is I'm getting the error message described above (it includes a beautiful crash) every time a Timer calls this function:
func updateTime() {
let currentTime = Int(player.currentTime)
let minutes = currentTime/60
let seconds = currentTime - minutes * 60
if seconds < 10 {
tempo.text = String(minutes) + ":0" + String(seconds)
} else {
tempo.text = String(minutes) + ":" + String(seconds)
}
durationSliderOutlet.value = Float(player.currentTime)
if currentTime == Int(player.duration - 1) {
playpauseOutlet.setTitle("Play", for: .normal)
isPlaying = false
}
print("currentTime: \(currentTime)")
print(Int(player.duration))
print("minutes: \(minutes)")
print("seconds: \(seconds)")
print(isPlaying)
}
I'm just trying to display the current time of an audio file in a label, and if I comment out this code
if seconds < 10 {
tempo.text = String(minutes) + ":0" + String(seconds)
} else {
tempo.text = String(minutes) + ":" + String(seconds)
}
...everything works just fine!
The second one throws the same crash and error when I press a button...
#IBAction func playpauseButton(_ sender: UIButton) {
if isPlaying == false {
playpauseOutlet.setImage(#imageLiteral(resourceName: "pause.png"), for: .normal)
player.play()
isPlaying = true
} else {
playpauseOutlet.setImage(#imageLiteral(resourceName: "play.png"), for: .normal)
player.pause()
isPlaying = false
}
}
Note: (#imageLiteral(resourceName: "play.png") appears as a little white rectangle. And if I try something like playpauseOutlet.setImage(UIImage(named: "play.png"), for: .normal) it also crashes.
What I'm pretending to do with this code is to change the "play" image of a button to "pause" image or vice versa depending of the isPlaying state. Thank in advance!